soft touch

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who is easily persuaded or taken advantage of.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A person or group which is sympathetic, accommodating, easily overcome, or easily persuaded, especially one which loans or readily gives money to another.
• noun idiomatic A comfortable situation; an easy task or undemanding occupation, especially one which is comfortably remunerative.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a person who is gullible and easy to take advantage of